/*
 * jdapimin.c
 *
 * Copyright (C) 1994-1995, Thomas G. Lane.
 * This file is part of the Independent JPEG Group's software.
 * For conditions of distribution and use, see the accompanying README file.
 *
 * This file contains application interface code for the decompression half
 * of the JPEG library.  These are the "minimum" API routines that may be
 * needed in either the normal full-decompression case or the
 * transcoding-only case.
 *
 * Most of the routines intended to be called directly by an application
 * are in this file or in jdapistd.c.  But also see jcomapi.c for routines
 * shared by compression and decompression, and jdtrans.c for the transcoding
 * case.
 */

#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"


/*
 * Initialization of a JPEG decompression object.
 * The error manager must already be set up (in case memory manager fails).
 */

GLOBAL void
jpeg_create_decompress( j_decompress_ptr cinfo ) {
    int i;

    /* For debugging purposes, zero the whole master structure.
     * But error manager pointer is already there, so save and restore it.
     */
    {
        struct jpeg_error_mgr * err = cinfo->err;
        MEMZERO( cinfo, SIZEOF( struct jpeg_decompress_struct ) );
        cinfo->err = err;
    }
    cinfo->is_decompressor = TRUE;

    /* Initialize a memory manager instance for this object */
    jinit_memory_mgr( (j_common_ptr) cinfo );

    /* Zero out pointers to permanent structures. */
    cinfo->progress = NULL;
    cinfo->src = NULL;

    for ( i = 0; i < NUM_QUANT_TBLS; i++ ) {
        cinfo->quant_tbl_ptrs[i] = NULL;
    }

    for ( i = 0; i < NUM_HUFF_TBLS; i++ ) {
        cinfo->dc_huff_tbl_ptrs[i] = NULL;
        cinfo->ac_huff_tbl_ptrs[i] = NULL;
    }

    /* Initialize marker processor so application can override methods
     * for COM, APPn markers before calling jpeg_read_header.
     */
    jinit_marker_reader( cinfo );

    /* And initialize the overall input controller. */
    jinit_input_controller( cinfo );

    /* OK, I'm ready */
    cinfo->global_state = DSTATE_START;
}


/*
 * Destruction of a JPEG decompression object
 */

GLOBAL void
jpeg_destroy_decompress( j_decompress_ptr cinfo ) {
    jpeg_destroy( (j_common_ptr) cinfo );/* use common routine */
}


/*
 * Abort processing of a JPEG decompression operation,
 * but don't destroy the object itself.
 */

GLOBAL void
jpeg_abort_decompress( j_decompress_ptr cinfo ) {
    jpeg_abort( (j_common_ptr) cinfo );/* use common routine */
}


/*
 * Install a special processing method for COM or APPn markers.
 */

GLOBAL void
jpeg_set_marker_processor( j_decompress_ptr cinfo, int marker_code,
                           jpeg_marker_parser_method routine ) {
    if ( marker_code == JPEG_COM ) {
        cinfo->marker->process_COM = routine;
    } else if ( marker_code >= JPEG_APP0 && marker_code <= JPEG_APP0 + 15 ) {
        cinfo->marker->process_APPn[marker_code - JPEG_APP0] = routine;
    } else {
        ERREXIT1( cinfo, JERR_UNKNOWN_MARKER, marker_code );
    }
}


/*
 * Set default decompression parameters.
 */

LOCAL void
default_decompress_parms( j_decompress_ptr cinfo ) {
    /* Guess the input colorspace, and set output colorspace accordingly. */
    /* (Wish JPEG committee had provided a real way to specify this...) */
    /* Note application may override our guesses. */
    switch ( cinfo->num_components ) {
        case 1:
            cinfo->jpeg_color_space = JCS_GRAYSCALE;
            cinfo->out_color_space = JCS_GRAYSCALE;
            break;

        case 3:
            if ( cinfo->saw_JFIF_marker ) {
                cinfo->jpeg_color_space = JCS_YCbCr;/* JFIF implies YCbCr */
            } else if ( cinfo->saw_Adobe_marker ) {
                switch ( cinfo->Adobe_transform ) {
                    case 0:
                        cinfo->jpeg_color_space = JCS_RGB;
                        break;
                    case 1:
                        cinfo->jpeg_color_space = JCS_YCbCr;
                        break;
                    default:
                        WARNMS1( cinfo, JWRN_ADOBE_XFORM, cinfo->Adobe_transform );
                        cinfo->jpeg_color_space = JCS_YCbCr;/* assume it's YCbCr */
                        break;
                }
            } else {
                /* Saw no special markers, try to guess from the component IDs */
                int cid0 = cinfo->comp_info[0].component_id;
                int cid1 = cinfo->comp_info[1].component_id;
                int cid2 = cinfo->comp_info[2].component_id;

                if ( ( cid0 == 1 ) && ( cid1 == 2 ) && ( cid2 == 3 ) ) {
                    cinfo->jpeg_color_space = JCS_YCbCr;
                }                        /* assume JFIF w/out marker */
                else if ( cid0 == 82 && cid1 == 71 && cid2 == 66 ) {
                    cinfo->jpeg_color_space = JCS_RGB;
                }                      /* ASCII 'R', 'G', 'B' */
                else {
                    TRACEMS3( cinfo, 1, JTRC_UNKNOWN_IDS, cid0, cid1, cid2 );
                    cinfo->jpeg_color_space = JCS_YCbCr;/* assume it's YCbCr */
                }
            }
            /* Always guess RGB is proper output colorspace. */
            cinfo->out_color_space = JCS_RGB;
            break;

        case 4:
            if ( cinfo->saw_Adobe_marker ) {
                switch ( cinfo->Adobe_transform ) {
                    case 0:
                        cinfo->jpeg_color_space = JCS_CMYK;
                        break;
                    case 2:
                        cinfo->jpeg_color_space = JCS_YCCK;
                        break;
                    default:
                        WARNMS1( cinfo, JWRN_ADOBE_XFORM, cinfo->Adobe_transform );
                        cinfo->jpeg_color_space = JCS_YCCK;/* assume it's YCCK */
                        break;
                }
            } else {
                /* No special markers, assume straight CMYK. */
                cinfo->jpeg_color_space = JCS_CMYK;
            }
            cinfo->out_color_space = JCS_CMYK;
            break;

        default:
            cinfo->jpeg_color_space = JCS_UNKNOWN;
            cinfo->out_color_space = JCS_UNKNOWN;
            break;
    }

    /* Set defaults for other decompression parameters. */
    cinfo->scale_num = 1;   /* 1:1 scaling */
    cinfo->scale_denom = 1;
    cinfo->output_gamma = 1.0;
    cinfo->buffered_image = FALSE;
    cinfo->raw_data_out = FALSE;
    cinfo->dct_method = JDCT_DEFAULT;
    cinfo->do_fancy_upsampling = TRUE;
    cinfo->do_block_smoothing = TRUE;
    cinfo->quantize_colors = FALSE;
    /* We set these in case application only sets quantize_colors. */
    cinfo->dither_mode = JDITHER_FS;
#ifdef QUANT_2PASS_SUPPORTED
    cinfo->two_pass_quantize = TRUE;
#else
    cinfo->two_pass_quantize = FALSE;
#endif
    cinfo->desired_number_of_colors = 256;
    cinfo->colormap = NULL;
    /* Initialize for no mode change in buffered-image mode. */
    cinfo->enable_1pass_quant = FALSE;
    cinfo->enable_external_quant = FALSE;
    cinfo->enable_2pass_quant = FALSE;
}


/*
 * Decompression startup: read start of JPEG datastream to see what's there.
 * Need only initialize JPEG object and supply a data source before calling.
 *
 * This routine will read as far as the first SOS marker (ie, actual start of
 * compressed data), and will save all tables and parameters in the JPEG
 * object.  It will also initialize the decompression parameters to default
 * values, and finally return JPEG_HEADER_OK.  On return, the application may
 * adjust the decompression parameters and then call jpeg_start_decompress.
 * (Or, if the application only wanted to determine the image parameters,
 * the data need not be decompressed.  In that case, call jpeg_abort or
 * jpeg_destroy to release any temporary space.)
 * If an abbreviated (tables only) datastream is presented, the routine will
 * return JPEG_HEADER_TABLES_ONLY upon reaching EOI.  The application may then
 * re-use the JPEG object to read the abbreviated image datastream(s).
 * It is unnecessary (but OK) to call jpeg_abort in this case.
 * The JPEG_SUSPENDED return code only occurs if the data source module
 * requests suspension of the decompressor.  In this case the application
 * should load more source data and then re-call jpeg_read_header to resume
 * processing.
 * If a non-suspending data source is used and require_image is TRUE, then the
 * return code need not be inspected since only JPEG_HEADER_OK is possible.
 *
 * This routine is now just a front end to jpeg_consume_input, with some
 * extra error checking.
 */

GLOBAL int
jpeg_read_header( j_decompress_ptr cinfo, boolean require_image ) {
    int retcode;

    if ( ( cinfo->global_state != DSTATE_START ) &&
        ( cinfo->global_state != DSTATE_INHEADER ) ) {
        ERREXIT1( cinfo, JERR_BAD_STATE, cinfo->global_state );
    }

    retcode = jpeg_consume_input( cinfo );

    switch ( retcode ) {
        case JPEG_REACHED_SOS:
            retcode = JPEG_HEADER_OK;
            break;
        case JPEG_REACHED_EOI:
            if ( require_image ) {/* Complain if application wanted an image */
                ERREXIT( cinfo, JERR_NO_IMAGE );
            }
            /* Reset to start state; it would be safer to require the application to
             * call jpeg_abort, but we can't change it now for compatibility reasons.
             * A side effect is to free any temporary memory (there shouldn't be any).
             */
            jpeg_abort( (j_common_ptr) cinfo );/* sets state = DSTATE_START */
            retcode = JPEG_HEADER_TABLES_ONLY;
            break;
        case JPEG_SUSPENDED:
            /* no work */
            break;
    }

    return retcode;
}


/*
 * Consume data in advance of what the decompressor requires.
 * This can be called at any time once the decompressor object has
 * been created and a data source has been set up.
 *
 * This routine is essentially a state machine that handles a couple
 * of critical state-transition actions, namely initial setup and
 * transition from header scanning to ready-for-start_decompress.
 * All the actual input is done via the input controller's consume_input
 * method.
 */

GLOBAL int
jpeg_consume_input( j_decompress_ptr cinfo ) {
    int retcode = JPEG_SUSPENDED;

    /* NB: every possible DSTATE value should be listed in this switch */
    switch ( cinfo->global_state ) {
        case DSTATE_START:
            /* Start-of-datastream actions: reset appropriate modules */
            ( *cinfo->inputctl->reset_input_controller )( cinfo );
            /* Initialize application's data source module */
            ( *cinfo->src->init_source )( cinfo );
            cinfo->global_state = DSTATE_INHEADER;
            /*FALLTHROUGH*/
        case DSTATE_INHEADER:
            retcode = ( *cinfo->inputctl->consume_input )( cinfo );
            if ( retcode == JPEG_REACHED_SOS ) {/* Found SOS, prepare to decompress */
                /* Set up default parameters based on header data */
                default_decompress_parms( cinfo );
                /* Set global state: ready for start_decompress */
                cinfo->global_state = DSTATE_READY;
            }
            break;
        case DSTATE_READY:
            /* Can't advance past first SOS until start_decompress is called */
            retcode = JPEG_REACHED_SOS;
            break;
        case DSTATE_PRELOAD:
        case DSTATE_PRESCAN:
        case DSTATE_SCANNING:
        case DSTATE_RAW_OK:
        case DSTATE_BUFIMAGE:
        case DSTATE_BUFPOST:
        case DSTATE_STOPPING:
            retcode = ( *cinfo->inputctl->consume_input )( cinfo );
            break;
        default:
            ERREXIT1( cinfo, JERR_BAD_STATE, cinfo->global_state );
    }
    return retcode;
}


/*
 * Have we finished reading the input file?
 */

GLOBAL boolean
jpeg_input_complete( j_decompress_ptr cinfo ) {
    /* Check for valid jpeg object */
    if ( ( cinfo->global_state < DSTATE_START ) ||
        ( cinfo->global_state > DSTATE_STOPPING ) ) {
        ERREXIT1( cinfo, JERR_BAD_STATE, cinfo->global_state );
    }
    return cinfo->inputctl->eoi_reached;
}


/*
 * Is there more than one scan?
 */

GLOBAL boolean
jpeg_has_multiple_scans( j_decompress_ptr cinfo ) {
    /* Only valid after jpeg_read_header completes */
    if ( ( cinfo->global_state < DSTATE_READY ) ||
        ( cinfo->global_state > DSTATE_STOPPING ) ) {
        ERREXIT1( cinfo, JERR_BAD_STATE, cinfo->global_state );
    }
    return cinfo->inputctl->has_multiple_scans;
}


/*
 * Finish JPEG decompression.
 *
 * This will normally just verify the file trailer and release temp storage.
 *
 * Returns FALSE if suspended.  The return value need be inspected only if
 * a suspending data source is used.
 */

GLOBAL boolean
jpeg_finish_decompress( j_decompress_ptr cinfo ) {
    if ( ( ( cinfo->global_state == DSTATE_SCANNING ) ||
          ( cinfo->global_state == DSTATE_RAW_OK ) && !cinfo->buffered_image ) ) {
        /* Terminate final pass of non-buffered mode */
        if ( cinfo->output_scanline < cinfo->output_height ) {
            ERREXIT( cinfo, JERR_TOO_LITTLE_DATA );
        }
        ( *cinfo->master->finish_output_pass )( cinfo );
        cinfo->global_state = DSTATE_STOPPING;
    } else if ( cinfo->global_state == DSTATE_BUFIMAGE ) {
        /* Finishing after a buffered-image operation */
        cinfo->global_state = DSTATE_STOPPING;
    } else if ( cinfo->global_state != DSTATE_STOPPING ) {
        /* STOPPING = repeat call after a suspension, anything else is error */
        ERREXIT1( cinfo, JERR_BAD_STATE, cinfo->global_state );
    }
    /* Read until EOI */
    while ( !cinfo->inputctl->eoi_reached ) {
        if ( ( *cinfo->inputctl->consume_input )( cinfo ) == JPEG_SUSPENDED ) {
            return FALSE;
        }               /* Suspend, come back later */
    }
    /* Do final cleanup */
    ( *cinfo->src->term_source )( cinfo );
    /* We can use jpeg_abort to release memory and reset global_state */
    jpeg_abort( (j_common_ptr) cinfo );
    return TRUE;
}
